How Ship Noise Reduces Whale "Acoustic Habitat"

I first saw this animation by the folks at Cornell University's Bioacoustics program at the 2009 Society for Marine Mammals conference, and it blew my mind.  It's a visualization of how a whale's ability to be heard by other whales is effected by the noise of cargo ships moving through its space.  The calling whales in this video are represented by the little blue dots, while the noise of the cargo ships are the bigger, red dots.  The color of the dots symbolizes how noisy something is.  The whales are light blue because they are not very loud, and the ships are red because they are loud. The dots representing the ships also appear to be bigger, because their sound carries further.  You can see that when a ship passes by the little blue dot representing a calling whale, the whale's call is completely overshadowed by the ship noise.  The funny rectangle shape in this animation is the border of the Stellwagen Bank National Marine Sanctuary. The link below the video leads to more information from Scientific American.

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New Age Science: Magic Crystals and Whale Songs

It is unclear if these people

have a permit, but their lack

of clothing is very clear

Whale song - almost everyone's heard it somewhere.  It's especially prevalent on new-age CDs, usually combined with the sounds of the pan flute.  Scientists don't generally play wind instruments to whales: it's actually illegal to play sounds to whales without a permit in the United States.  Recording whale song is not illegal, as long as you don't get closer to the whale than 100 yards.  But how does the whale's song get from the whale into your iphone?

I've already talked a little about how dolphins produce sound.  The method of sound production for whales is less well understood, so let's just start with the sound once it leaves the whale's body and enters the water.

A humpback whale and
hydrophone, photo by
Flip Nicklin

Like most sound, the sounds of whale songs are a result of vibrations.  These vibrations compress and expand molecules in the the water around the whale, so the molecules are squeezed together and then spread apart.  What we think of as "sound waves" are really a measure of the amount of pressure on the molecules in the water.  This is similar to what happens when you hum: as the vocal chords in your throat move back and forth, they create changes in pressure in the air around you. Here's a little video showing how molecules are moving when you hear a sound:



The applause for "Sound and Pressure" in this video is particularly poignant.

We can't usually feel the pressure of sound waves anywhere but our ears, unless the sound is really loud, like when you stand too close to the speakers at a rock concert.

Quartz, topaz, salt, sucrose (table sugar),

bone, and even silk have piezoelectric

properties. Smashing raw quartz against
the head not recommended to activate
these properties.

Now we know that sound is made of pressure waves, but how can we convert those pressure waves into the electrical signal we need for our recorder?  This is where the new-age folks would really get excited: we're going to use some "magic" crystals.  In 1881, a man named Gabriel Lippmann came up with the idea that if we squeeze certain types of "charged" crystals, we can create an electrical current.  This theory was later demonstrated by the famous Curie family, of radioactive fame.

Charged crystals are made up of thousands of molecules, each of which has a positive and negative charge.  When the molecules are "relaxed" (when you're not squeezing them), the charges balance out.  However, when the crystal is squeezed or bent, the charges are forced together or apart, creating an electronic charge on one side of the crystal.  Modern piezoelectrics are generally made of ceramic, which are coated on either side with a thin layer of metal.  You can see a modern piezoelectric crystal if you dissect the earpiece on your headphones or a singing card from the grocery store.

Note: I found an almost identical figure on a creationism site, as evidence of creationism.  They claimed as evidence that quartz is the only natural piezoelectric material.  As we see above, this just isn't true.

Compression of the crystal
results in a change in electrical
charge, measured in volts (V).

The whale sound increases the pressure in the water.  This compresses the crystal, which creates an electronic charge on each side.  Wires attached to the crystal lead up to the computer on your boat, usually via a pre-amplifier.  A pre-amplifier is just what it sounds like - it makes things louder (amplifies them) before (pre) they go up the wire and into your computer.  Pre-amplifiers are sometimes necessary because the change in charge created by the crystal is too small to travel up a long wire.

Even when the electrical charge has gone all the way up the cable, and into the boat, it isn't done yet.  It still needs to be changed from an analog to a digital signal.  Today, we generally use computers and other digital devices (ipods, hard drives, etc) to store our data and music.  Analog data is continuous, like a sound wave.  Digital data is not continuous - it takes many many samples along a sound wave. In the figure below, we can see the analog sound (in blue) with the digital samples (red).  This is probably why many hipsters people think that records are better than digital sound - because digital recordings don't keep track of most of the sound wave.

A great example of analog recording is the vinyl record.  If you don't know what a record is, you're either very young or not a hipster.  When you play a vinyl record, a needle runs down a continuous groove in the record.  As the needle moves down the groove, it vibrates up and down.  These vibrations travel up the arm of the record player, and eventually to a piezoelectric crystal (you know this one already!).  The crystal converts the vibrations to an electric signal and sends them on to your speakers.

Scanning Electron microscope photograph of the groove

 in a record, by Chris Supranowitz.

In contrast, the data on a CD is stored digitally.  Each CD is engraved with millions of tiny dots and dashes, which your computer reads with a laser and translates into music.

Scanning Electron microscope photograph of a CD, 

by Chris Supranowitz.

After an analog to digital converter has changed our electrical signal into thousands of data points, we can finally listen (and look) at the recordings we've made. As it turns out, physics, chemistry, materials and electrical engineering, and biology have all been necessary to get the sound from the whale and into the computer.  Whether you're doing yoga (like my friend Sheldon) or desperately trying to finish your thesis, there's a lot of science behind those sounds!

Bottlenose dolphin recordings from my acoustic research.

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I am (in an evolving relationship with) Science.

*Warning: This post has photos of whale guts.  Be prepared.
I am science is an online movement that started with Kevin Zelnio's moving and heartfelt narrative about how he became a scientist.  The resulting tumblr feed, I am Science, is full of stories, long and short, about who scientists were before they were scientists, and who they are outside of science.  As a grad student, I don't really have much of a life outside of science.  In an interview a couple of months ago for a website giving advice to students interested in various careers, I was asked how I manage my free time, and my answer was a guffaw.  Lately I haven't seemed to have much time for anything but science, although I generally manage to squeeze in one fun event per weekend (last weekend it was the Valentine's Day Biathalon).

Image via etsy.com/shop/AfricanGrey

I think my relationship with science is a little bit like a human relationship.  I feel guilty when I neglect it to go out for a run - those files aren't going to analyze themselves!  At times, it feels like we spend so much time together that I forget why I fell in love with it in the first place.  I felt like we spent all our time together doing chores and errands, and weren't taking any time to enjoy each other.

Over the last couple of weeks, blogging has been to me what a romantic date might be to a relationship.  It's been my chance to take spend some quality time with marine biology and have a little silly fun together.  My relationship with science is suffering from grad school almost like a human relationship would (and does) when stress comes into play.  So I thought I would take a step back and look at how science and I found each other, to put our current relationship into a little perspective.

Dating

I am not one of those people who have wanted to a marine biologist their whole life.  In fact, when I meet marine biologists (especially people who study dolphins) who have wanted to study them since they were born, it kind of skeeves me out.  It's sort of like how I feel about marrying your childhood sweetheart - it's cute and sweet, but didn't you want to date a couple more guys first?  (Note: I am my boyfriend's first serious girlfriend, and he has wanted to study marine biology since he was 6.  This probably makes me a floozy).  

Aaaand bachelor number three is... Science!

5th grade crush on science.

Here's the list of things I wanted to be before I graduated from college:

1) Bear                              6) Novelist

2) Dog Trainer                  7) Othopedic Surgon

3) Olympic Skier               8) Water Quality Scientist

4) Marine Biologist           9) Marine Biologist

5) Journalist

You'll notice that Marine Biologist is in there twice - that's the 5th grade visit to the Monterey Bay Aquarium.  I think most kids go through a "marine biologist" stage - it's that damn dolphin thing.  For me, it was just a school-kid crush.

Going Steady

It was not until my last year of college that marine biology and I ran into each other again.  I had started college as a pre-med, but something wasn't clicking for me.  I think it was probably because most of our lab work was replicating experiments that had already been done to learn good lab technique - which is very important, but just didn't catch my imagination.  During my senior year I finally decided to take Marine Biology.  It was one of the best decisions I've ever made.  My professor, Dr. Joel Elliott, took the time to really expose his students to fieldwork.  Not only did we learn about plankton and haloclines (layers in the water where there is a change in salinity) in the classroom, but we went out in the Puget Sound and measured them.  We were encouraged to team up for class projects in which we learned something new about the biology of the Sound.  We were even allowed to try out cutting-edge technology, like the ROV (remotely operated vehicle).  Driving an ROV is similar to playing a video game with a joystick.  As you can see, I'm not great at video games:

The sea star I finally pick up there is a Pycnopodia helianthoides, which in

 latin means many-legged sunflower. Latin names are so cool sometimes.  

I wish every college student had this kind of opportunity - I think there would be more kids out there doing science if they actually got to DO science.  Not everyone can tag whales, but we know so little about the ecology of many things that everyone could do something.  Sorry, I digress.

Pisaster makes you crazy.

After my mini-project in Marine Biology, Joel allowed me to do an independent-study project on the predation of the ocre sea star Pisaster ocraceus on the invasive mussel Mytilus galloprovincialis.  Pisaster is the purple or orange sea star that you see all up and down the west coast of north America, and is very important in the ecology of the intertidal zone.  It wasn't a sexy project - I spent most of my time prying smelly sea stars off of a pier with a garden tool called the big dog, but fact that I could find out something new about the natural world really got me hooked on biology.

When I went to talk to my college advisor about graduate school, he took a look at my mediocre grades (physics just wasn't that exciting to me until I started applying it to underwater sound) and told me to go take some summer field classes at Bamfield Marine Science Centre.  I was obsessed with sea stars, but the invertebrate biology class was full, so I reluctantly agreed to take the Marine Birds class instead.  By the time there was an opening in Inverts, I was having so much fun driving around in boats and learning about bird biology that I decided to stay in the birds class.

Coasties are similar to mounties, but
with different uniforms.

One early Saturday morning, my friend Aija and I went out early to check on some birds we were thinking about doing our class project on.  On the way back, our motor failed.  Since no one at the marine station was awake yet, we ended up calling the coast guard for a tow back.  Canadian coast guard guys are both cute AND extremely polite, by the way.  After we filed our "broken motor" report back at the pier, we started talking to a few people at the dock.  They were going out to look for gray whales - would we like to come along?  Well, okay.  I guess.

The captain of the boat, Brian Gisborne, runs a water taxi service between the tiny coastal communities of Port Renfro and Bamfield.  He's lived in the area all his life, and has really great insight about the local biology.  Although he doesn't have a college degree, he's yet another example of how regular people can contribute to science, and has coauthored a book and several scientific papers.  Brian had some great ideas for bird research, and I ended up doing my class project on the association between marbled murrelets (a little seabird) and gray whales.  Both Aija and I eventually published our class projects, which is a testament to the both the seabirds class and Brian's wonderful mentorship (Aija's paper, and mine).

Brian was a contractor with the Cascadia Research collective, and at the end of my time at Bamfield he helped me obtain an internship with them.  When young scientists ask me how they can get into marine biology, I ALWAYS tell them to do an internship - working with Cascadia was truly a chance in a lifetime.  I got to try out a variety of different types of marine mammal research, from dissections of dead seals, sea lions, whales, and porpoises, to photo identification and acoustics.  It was also an opportunity to be mentored by very dedicated and professional scientists.

Whale necropsies require galoshes and a strong stomach.  Tissue samples from
the internal organs of this dead-stranded whale were used to determine
the whale's disease, parasite, and health status.

Commitment

Although I had applied to one graduate school right out of college, I didn't get in.  At a loss for what to do with ourselves, my boyfriend and I moved to Santa Cruz, where we both worked in retail and tourism jobs.  Working at a retail store really put my life into perspective - I did NOT want to spend the rest of my life hanging up clothes and telling people whether their outfits coordinated (and if you've seen me dress, you know I am the worst person in the world to ask).  Fortunately, I was still able to do some volunteering with Cascadia.  I spent a month with Scripps Researcher Elizabeth Henderson aboard the R/P FLIP ship, a mobile research platform that actually goes from a horizontal to a vertical position by partially filling with water. It sounds like fantasy, but I assure you I am not making this up.  The FLIP is really great for bioacoustic and oceanographic research, because all of the noisy parts are above the water.  While I wasn't on FLIP, I got my marine biology fix by volunteering at the Monterey Bay Aquarium (in the penguin exhibit) and with a shark research group.  Finally, in 2007, I was accepted to the University of Hawaii, and started on my way to being a bioacoustition.

Aboard the FLIP 

Part of the penguin exhibit (left) and measuring bat rays in the Elkhorn Slough.

So, what has been the point of this long, self involved trip down memory lane?  Reminiscing about the changing dynamics and expectations in my relationship with science puts my current position in perspective.  I may have ended up where I thought I would, but it turns out I never really knew where I was going - and it turned out to be pretty damn cool.

Young Ken Norris (left) at the start of
 his career as a cetacean biologist.
Scanned from The Porpoise Watcher.

It's always good to have a relationship role model when things are tough.  For my relationship with science, I look to Kenneth S. Norris.  Ken Norris is one of the more famous cetacean researchers, for his work with Hawaiian Spinner dolphins and groundbreaking ideas on hearing.  He even has a lifetime award for excellence in marine mammal research named after him.  He didn't start out in cetacean research - he began by studying discovered circadian rhythms in snakes and the function of color changes in reptiles and amphibians.  It wasn't until he was in his mid-30s that he started studying cetaceans.  No one who knew him when he was my age could have predicted that one day he would be a world-renowed dolphin expert.  In case you think this example just pertains to biologists, consider the fact that Rosalind Franklin, one of the discoverers of the structure of DNA, did her original research on coal.

Much like science itself, our relationships with science are not static.  They change and evolve, and the lifetime journey through science is unpredictable.  The knowledge that we gain about one aspect of science gives us perspective about other areas.  This rough patch I'm going through isn't going to last forever, and my love for science is only going to be stronger with greater understanding (cue "My Heart Will Go On").

Oh yeah, and those people on I am Science?  Finding science is only the beginning - they're going to take it to a whole new level.

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Right Whale Sound Exposure

This is a great graphic from National Geographic showing potential sources of sound that a right whale could be exposed to.  That's a lot of noise!  View full size here.

I love you, Marine Biology!

Happy Valentine's Day!  Here's a (totally realistic)
depiction of ocean love via my mom.

Beware the Hipster Biologist

When you study something as popular as dolphins, sometimes it is very hard to get people to take what you do as a scientist as seriously as you would like. I imagine the same thing happens to people who study rainbows, panda bears, penguins, or any other subject, including just overall marine biology, that is considered cool or cute by the mainstream public (aka people who don't also study that subject). People who study string theory or nuclear physics possibly experience the opposite phenomenon - people hear what they do, and immediately assume that they won't understand anything about it. I experience a little bit of both extremes, being as I study dolphins and whales ("theyareSOCUTE!") and bioacoustics ("Uhhh...I'm going to go back to playing Angry Birds now.") Yes, I was able to find a picture of a cheerleader whale and a hipster dolphin. God bless the internets.

Hipster dolphin via holycrapitsaustin.com/

I have often been guilty of scientific hipsterism. Just read my first blog post - and replace the words "dolphin" and "sea star" with "Lady Gaga" and "Static Portal"(an obscure band name I just made up).

Yeah, I really like Lady Gaga/dolphins now, but only because I liked Static Portal/echinoderms first and couldn't get into the show/class. 

I really like Lady Gaga/dolphins, but only because I understand the deeper meanings behind them. 

 You don't even have to study dolphins to be a science hipster.

I only care about Static Portal/echinoderms, Lady Gaga/dolphin research is SO mainstream.

In my personal experience, hipster attitudes come across as very elitist, and discourage people from learning more about science. Does it really matter what species got you interested in marine conservation? In the end, what really matters is a willingness to learn about issues affecting the health of the oceans, and a realization that it takes a healthy ecosystem to maintain healthy oceans.

Some of the best examples of how my hipster attitudes about science have effected my real life interaction with non-science people have occurred on airplanes.

Conversation 1:

34B: So, what do you do?

Me: Oh, I study whales and dolphins.

34B: OH, I just LOVE dolphins. I swam with one once and it looked deep into my eyes and whispered that it loved me.

Me: Well, you obviously don't understand cetaceans on the deep and meaningful level that I do - I think I might take a nap.

Nice talking to you!

Conversation 2:

34B: So, what do you do?

Me: You see, right now I'm writing this GREAT computer program in MatLab that uses this obscure form of Fast Fourier-Transform to...

34B: Zzzzzzzzzzzz.

When I really look at it, I am the loser in both of these situations. Here I am, with the opportunity to communicate to a member of the public about the wonderful research that I do, and my silly hipster attitudes are getting in the way! (In case you think this is not worth your time to talk to people on airplanes, I know a guy who once sat next to the head of a funding agency and ended up with grant money with the next 10 years). In both cases, I'm failing in two ways: 1) by judging people who are "mainstream" in their exposure to my specialty or 2) by championing my somewhat obscure interests without first taking into account another perspective.

There is a very good, old fashioned book that my dad often refers to. It's called "How to Win Friends and Influence People," and was written in 1936, near the end of the great depression, by Dale Carnagie to help salesmen. Although that might make you think that it is full of slimy tricks to sell vacuums, most of it is common sense. For example, Principle #8 is

"Talk in terms of the other person's interest."

It goes against the whole principle of hipsterism - that we should use the interests of the mainstream to draw them in to deeper aspects of our hipster culture. In the end, though, wouldn't it be better if we started these conversations with an open mind? The person sitting next to me in 34B might be the daughter of the vice-president of a tug boat company and LOVE the idea of doing dolphin research off their vessels. Or they might decide to eat organic after learning that pesticide runoff is poisoning killer whales in Washington State. When we scientists can knock off the posturing, and open up to each other and non-scientists, we'll all win.

But I do want a pair of those cool glasses.

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Honolulu to Kauai in One Minute

Twice a month, I sail on a shipping tug from Honolulu to either Kauai or the Big Island. On the way, I collect acoustic and GPS data on whales and dolphins. For those of you who haven't spent the night on a tug boat crossing the Kaʻieʻie Waho channel, here's a taste of what it's like (if it was sped up a LOT and you skipped the night-time part AND had really nice weather).

iTimelapse is really fun. :)


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Dolphins on Helium

When you or I breathe helium at a birthday party, we get fun, squeaky munchkin voices. That's pretty fun, but what would happen if you gave helium to a dolphin? Cetacean scientists have done just that, and it wasn't because they'd been playing too much beer-pong .

What possible reason (other than the fact it's totally hilarious) could marine mammal scientists have to give a dolphin helium? For the answer, we first have to know a little bit about dolphin behavior.

In the wild, dolphins can dive hundreds of feet deep. At those kinds of depths, gasses get compressed and become more dense. The compression of gasses is one reason why human divers rarely go that deep. As the air is compressed, the molecules of the air get closer together, and the air takes up less space. Dolphins have actually evolved the ability to let their lungs collapse as the air compresses, which has a side benefit of making them less bouyant and making diving easier!(1) The picture at right (from Moore et al(2), 2011) shows a cat-scan of a dolphins lung as it compresses under pressure.

How does helium come into all of this? Helium affects our voices because it is lighter than air. At depth, the air in a dolphin's lungs is heavier than normal air - pretty much the opposite of the effect of helium. So we could expect the effect of deep diving on a dolphin's 'voice' to be the opposite of breathing helium on a human's voice. The opposite of breathing Helium for a human is breathing Sulfer Hexaflouride, a gas which is heavier than air. Do NOT try this at home.

Dolphin communication underwater should theoretically be effected somewhat like it affects the mythbusters guy - they should sound like scary Dolphin Terminators. Let's see what actually happened...

The two whistles are a little bit different(3), but neither of these sounds anything like Barry White. What gives? The reason dolphins are not effected by compressed air the way we think they should be lies in the difference between the way humans and dolphins make sounds. In real life (as opposed to on Flipper, whose voice was done by a monkey), dolphins communicate mainly through high-pitched whistles. Dolphin whistles are produced by changing the air pressure around an organ inside of the dolphin’s head. (Most toothed whales actually have two of these organs, but animals in the sperm whale family do not). This organ looks a little bit like a pair of lips, and functions a little bit like them too(4), as we’ll see in a minute.

To produce a whistle, the dolphin changes the air pressure around the phonic lips, something like you or I would blow air through our lips to make a “raspberry” sound. As you tighten the muscles in your lips while blowing air through them, you change how fast your lips flap, changing the pitch of the sound. In addition, every video in existence on lip buzzing includes a creepy-looking mustache.

Dolphins are doing this same sort of thing, but inside their heads!

Human voices, unlike dolphin 'voices,' are effected by the way sound bounces around inside our throat and mouth. Helium increases the speed of sound inside your mouth, which changes the way the sound waves bounce around in there. When the sound actually gets out of your mouth, you sound really funny. This video by the Naked Scientists explains it really well:

The sounds dolphins make don't bounce around in an air space before the leave the dolphin's head, so they sound exactly the same with and without helium.

And that, my friends, is why dolphins aren't actually much fun at a party.

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1 Skrovan, R.C., Williams, T.M., Berry, P.S., Moore, P.W., and Davis, R.W. 1999. The diving physiology of bottlenose dolphins (Tursiops truncatus) II. Biomechanics and changes in buoyancy at depth. Journal of Experimental Biology 202: 2749-2761.

2 Moore, M.J., Hammar, T., Arruda, J., Cramer, S., Dennison, S., Montie, E., and Fahlman, A. 2011. Hyperbaric computer tomographic measurement of lung compression in seals and dolphins. Journal of Experimental Biology 214: 2390-2397.

3 Madsen P.T., Jensen F.H., Carder D. and Ridgway, S. 2011. Dolphin whistles: a functional misnomer revealed by heliox breathing".Biology Letters, doi:10.1098/rsbl.2011.0701

4 Cranford, T.W., Elsberry, W.R., VanBonn, W.G., Jeffress, J.A., Chaplin, M.S., Blackwood, D.J., Carder, D.A., Kamolnick, T., Todd, M.A., and Ridgeway, S.H. 2011. Observation and analysis of sonar signal generation in the bottlenose dolphin (Turciops truncatus): Evidence for two sonal sources. Journal of Experimental Biology 407: 81-96.

This post was inspired by Paul Nachtigall's Seminar and:

Jensen F.H., Perez J. M., Johnson M., Aguilar Soto N. and Madsen P.T.(2011) , "Calling under pressure: short-finned pilot whales make social calls during deep foraging dives".Proceedings of the Royal Society B. doi: 10.1098/rspb.2010.2604.

NOW you've opened Pandora's Box

Last week I had the opportunity to do a guest post over at the Deep Sea News. It was so much fun that I decided to try doing some more blogging at my own site. If you'd like to see that post, click here:

Guest Post: True Confessions of a Dolphin-Loving Marine Biologist

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